Science First Look

Scientists discover bizarre molten iron 'jet stream' in Earth's core

Measurements made by Europe's Swarm satellites suggest a river of liquid iron deep within the Earth.

An artist’s representation shows the movement of the jet stream in Earth’s core.
ESA | Caption

Scientists from Denmark and Britain were astonished when Europe’s fleet of Swarm satellites detected signs of a swiftly moving river of molten metal within Earth’s core, similar to the atmosphere’s jet stream, but buried thousands of miles below our feet.

This westward-flowing jet is important to the global magnetic field, researchers say, and learning more about the river of metal could help explain why the Earth’s magnetic field has changed throughout Earth history.

“It’s a remarkable discovery,” said Phil Livermore of the University of Leeds in Britain, who led the team, according to New Scientist. “We’ve known that the liquid core is moving around, but our observations haven’t been sufficient until now to see this significant jet.”

Researchers attribute the discovery to the three European Space Agency Swarm satellites, launched in 2013, which gather information about Earth's magnetic field.

Those three satellites detected two areas of magnetic flux in the originating from the boundary between the core and mantle, a phenomenon that scientists determined must be due to the movement of molten metal. It is the flow of molten iron in the Earth’s outer core that gives our world a magnetic field, and scientists were able to track the molten jet through shifts in the magnetic field.

In the atmosphere, the jet stream is a rapid "river of air" that helps speed airplanes along to their destinations. In the Earth’s core, the 260 mile-wide metal jet moves about 30 miles per year, estimated the scientists. That may seem snail-like, but it's positively speedy for liquid iron. The New Scientist reports that the stream’s speed appears to have tripled since 2000.

“That might not sound like a lot to you on Earth's surface, but you have to remember this a very dense liquid metal and it takes a huge amount of energy to move this thing around and that's probably the fastest motion we have anywhere within the solid Earth,” the Technical University of Denmark’s Chris Finlay told the BBC.

The jet is located approximately 1,800 miles beneath Alaska and Siberia, and currently spans about half of the planet, according to scientists. And it isn’t a new phenomenon, either. Study authors say that it is likely to have been in operation for hundreds of millions of years.

They say it is formed by swirling cylinders of molten iron in the outer core, which function as rollers to squish out more iron from the inner core as they push up against it.

Researchers say that this discovery is exciting, in part, because of what it says about the future of core research.

“We know more about the Sun than the Earth’s core,” said Dr. Finlay. “The discovery of this jet is an exciting step in learning more about our planet’s inner workings.”